To learn how peripheral and central nervous system taste neurons are influenced by environmental factors, neurophysiological responses will be recorded from single neurons in the chorda tympani nerve, the nucleus of the solitary tract (NST) and parabrachial nuclei (PBN) in rats fed a NaCl-deficient diet during early development. The period of deprivation will extend from 3 days gestation to prepubertal ages or to adulthood. Therefore, the effects of deprivation period on functional responses will be examined for each neural level. Moreover, the "plasticity" of the gustatory system will be studied by recording taste responses from rats initially deprived of dietary NaCl to prepubertal ages or to adulthood and then fed a NaCl-replete diet for at least 20 days. As a correlate to these neurophysiological experiments, a behavioral study will be conducted to learn whether qualitative characteristics of salt stimuli are affected by early NaCl deprivation. The proposed studies will provide new information on: 1) how response characteristics of single taste neurons are affected by prolonged periods of NaCl deprivation, 2) the extent to which neurophysiological taste responses in rats initially deprived of dietary NaCl appear to be normal after they are then fed a NaCl- replete diet, 3) how deprivation effects differ among chorda tympani, NST and PBN neurons, and 4) the behavioral consequences of early NaCl deprivation. The results will provide new information on the development of peripheral and CNS taste responses, and correlative taste-guided behaviors, that relate to the development of taste preferences and aversions and to the development of ingestive behaviors.